(a) Field of the Invention
The present invention relates a transparent electrode etchant composition and an etching method using the same.
(b) Description of the Related Art
Indium oxide layers, particularly indium zinc oxide (hereafter referred to as “IZO”) layers and indium tin oxide (hereafter, referred to as “ITO”) layers, are used as a transparent electrodes for various electronic products.
To form an IZO or ITO transparent electrode, and IZO or ITO layer is generally deposited on an insulation substrate by sputtering, a photoresist is then coated thereon and is exposed and developed to form a photoresist pattern. The indium oxide layer is then etched by using the photoresist pattern.
The indium oxide layer typically has excellent chemical resistance, and therefore is a material that is hard to etch. Examples of etchants used to etch indium oxide layers include a nitro-hydrochloric acid (HCl+HNO3) etchant disclosed Korea Patent Laid-Open Publication No. 1996-0031452, an etchant made of one material selected from hydrochloric acid, a weak acid, and an alcohol disclosed in Korea Patent Laid-Open Publication No. 1997-0065685, a FeCl3+HCl etchant disclosed in U.S. Pat. No. 5,456,795, and an etchant including oxalic acid and a salt thereof or aluminum chloride as a main component disclosed in Korea Patent Laid-Open Publication No. 2000-0017470.
Also, an etchant including HI and FeCl3 is disclosed in U.S. Pat. No. 5,340,491.
However, in the case of the nitro-hydrochloric acid etchant, although the cost of the etchant is low, in practice the etching is too fast at the side surface of the photoresist pattern, and as a result the profile of the side surface pattern is poor. In addition, the main component of the etchant, the hydrochloric acid and the nitric acid is easily volatilized, and thus the composition of the etchant can vary significantly over the course of time.
In the case of the FeCl3+HCl etchant, the main component is also hydrochloric acid, and the composition of the etchant can also vary significantly over the course of time.
With respect to etchants that include oxalic acid, although etching with such an etchant is easily executed, the solubility of oxalic acid is low at a low temperature such that precipitate may be generated.
In the case of the etchant that includes HI, the etching speed is fast and the side etching is relatively small, however the cost is high and toxicity and corrosion levels are high, such that the ability to use such etchants in actual processes is limited.
In addition, the above-described conventional etchants all have almost the same strong chemical activity, and as a result erosion of an adjacent metal having poor chemical resistance, such as copper (Cu), aluminum (Al), molybdenum (Mo), and chromium (Cr), may occur when the etchant is used.
These etchant are typically applied to multilayered structures that include at least one of the above-described metals.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.